I let them work on it for a minute or two then someone asked how many gallons in a litre. Perfect! I asked which holds more, 1 litre or 1 gallon? They could all picture a litre:
but a gallon is less familiar to them so I pulled up some pictures:
We all agreed that 1 gallon holds more. I wrote down the number of gallons in a litre and the number of litres in a gallon and let them work out the conversion.
We talked about checking the reasonableness of answers (which they are usually very good at). So if they are converting from gallons to litres, they should get a bigger number than the one they started with. Some have trouble understanding when to multiply and when to divide, but they can still check their answers and, if needed, recalculate.
Most decided they would rather carry 5.62 l of water because it would be easier to carry, but one student said he would rather carry the 1.85 gallons as he would have more water. So then I changed the question and asked something like "If you had to empty a big vat of water into another one 50 m away, would you rather carry the water using a 5.62 litre bucket or a 1.85 gallon bucket?" Throwing a context around the original question definitely makes a difference. I may change the question for next time...
Many students then continued their quiz. When each finished they worked on a literacy test package (all grade 10 students in Ontario must write a provincial literacy test), then on more linear and quadratic data, then on some balance benders. Some only completed the quiz. This is the challenge of giving students all the time they need to complete an assessment - you need to keep the ones who finish more quickly doing meaningful work that will not disadvantage those who need the extra time to complete the assessment.
Tomorrow we explore triangles with our 26 squares.
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